I. Field of the Invention
The present invention is directed to potentiometer type devices, and more particularly to a wiper or movable contact of a variable electrical resistor which is subjected to adverse operating conditions.
II. Description of the Related Art
Variable electrical resistors or potentiometers are well known and have been employed in many applications, typically to tap off a portion of a supply voltage, as in a dimmer switch for household lighting. The variable resistor basically includes an elongate electrical resistor which is connected across the supply voltage and a wiper slidable along the resistor in electrical contact with the resistor and electrically connected via a device to be controlled to one end of the resistor. Typically, the resistor is laid out along a circular arc and the wiper is mounted for rotation about the center of that arc.
Because the voltage output of the variable resistor is representative of the position of the wiper, such resistors have found many applications in electrical control or indicating circuits in which the position of a movable member within its range of movement controls the position of the wiper so that an electrical signal representative of the position of the movable member is established.
One example of such an application is that of a throttle position sensor used in automotive vehicles to supply a signal representative of the throttle position to the on-board computer which employs this signal in conjunction with others to control operation of the vehicle engine, automatic transmission, etc. In this application, the rotatable wiper of the variable resistor is mechanicallv directly coupled to the shaft which carries the throttle or air-flow regulating plate.
While the above prior art throttle position sensor devices have performed generally satisfactorily, certain deficiencies and advantages have been noted, as follows: